In Sell et al U.S. Pat. No. 4,567,149 issued Jan. 28, 1986, an apparatus and a related method for use in the diagnostic analysis of a liquid specimen through binding assays was disclosed. The apparatus included a rigid body and a plurality of elongated threads, sometimes also referred to as filaments and/or strips, each coated with a binding assay component and supported on the body in spaced relationship for simultaneous contact with a liquid specimen. The plurality of elongated threads was positioned across an elongated well formed in the rigid body, generally transverse to the well's longitudinal axis. A transparent member, hereafter referred to as a coverslip, secured to the rigid body enclosed the elongated well between an inlet and an outlet along a common reagent flow path from inlet to outlet. The threads were protected during handling of the apparatus.
In use, a specific volume of the liquid specimen could be confined and isolated in the well, where it can incubate with the threads. The apparatus of the invention was particularly suited for allergy screening, with each elongated thread being a cotton thread coated with a specific allergen.
The rigid body used in Sell et al preferably was formed of plastic and included a flat land surrounding the elongated well. The thread was tensioned across the well, from lands on opposite sides of the well. The coverslip overlaid the threads and was secured to the lands on opposite sides of the well. To facilitate insertion of various liquids into the well, including the liquid specimen to be tested, suitable washing solutions, and a labeled antibody solution, the rigid body included a port at each end of the elongated well. The apparatus further included a pipette projection in alignment with the port located at one end of the well.
The coverslip preferably included a thin plastic sheet in direct contact with the land of the rigid body. The coverslip had an overlaying a silk screen having a series of parallel narrow apertures, each aligned with a separate one of the cotton threads. The silk screen optimizes the measuring of the reaction of each cotton thread by reducing the interfering effects of adjacent threads. The coverslip was preferably secured to the land of the rigid body by an ultrasonic weld.
The Sell et al U.S. Pat. No. 4,567,149 device is widely accepted and still in successful use. In use, the support and threads are filled and incubated with a liquid specimen, such as human sera. A secondary antibody (for example antibody conjugated to horse radish peroxidase—which reacts with luminol)—is incubated for about four hours. Thereafter, the threads were washed with a buffer—a saline solution and drained. This washing occurred three times. After this step, a fluid, which induces a chemiluminescent reaction, is introduced. The amount of multiple biological agents interacting with the binding assay components coated on the threads is determined by noting the presence and absence of light being emitted from each of the wells. For example, when screening for the presence of multiple allergen-specific IgE class antibodies in a liquid sample, the device is incubated with the test sample and then, after washing, incubated with a solution containing labeled antibodies against the IgE class antibodies that have bound to the threads. The threads are then analyzed to determine the presence of the labeled antibodies. If the labeled antibodies are labeled with a radioactive tracer, such as 125I, this analysis can be accomplished using a gamma counter. Alternatively, the analysis can be accomplished by placing the threads adjacent to photographic film for exposure and by then measuring the degree of exposure or more recently by registration to a light detector, either fiber optic or by direct detection.
This device has experienced a high degree of commercial success. This disclosure is an improvement on that device. Specifically, we have undertaken a systematic and extensive analysis of this prior art device. In what follows, the reader will have enumerated the specific areas for improvement.
It is to be understood that we claim invention in both determining the following areas for improvement as well as the specific solutions, which we have adopted in this disclosure. It is well understood that the identification of issues to be resolved, as well as their solution, can constitute invention. Therefore, in so far as the prior art has not identified the issues we now enumerate, with the device of Sell et al U.S. Pat. No. 4,567,149, invention is claimed.